Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Intermediate lobe
Introduction
Pars intermedia is the boundary between the anterior and posterior lobes of the pituitary. It contains three types of cells – basophils, chromophobes, and colloid-filled cysts. The cysts are the remainder of Rathke’s pouch.
In human fetal life, this area produces melanocyte stimulating hormone or MSH which causes the release of melanin pigment in skin melanocytes (pigment cells). However, the pars intermedia is normally either very small or entirely absent in adulthood.
In lower vertebrates (fish, amphibians) MSH from the pars intermedia is responsible for darkening of the skin, often in response to changes in background color. This color change is due to MSH stimulating the dispersion of melanin pigment in dermal (skin) melanophore cells.
External links
- Histology image: 14001loa – Histology Learning System at Boston University
- Histology image: 14101loa – Histology Learning System at Boston University
- Histology at University of Southern California end/c_1
- Histology at University of Southern California end/c_11
- Template:OklahomaHistology
- Template:UIUCHistologySubject
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753